We propose to test the effectiveness of a new ultrasound imaging method for detection and screening of breast cancer with real data obtained from a scaled-down working scanner model featuring an electronically scanned transducer array. The complete transducer array will be a regular polygon constructed from 4 or 6 transducer arrays, each of 128 elements. Multiple transmitting and receiving multiplexer banks will allow strong incident fields to be produced, and rapid data acquisition. This design also provides high stability and freedom from vibration for the jitter- and drift-free data required for use by our very accurate inverse-scattering imaging algorithms. These algorithms are based upon computing the inverse-scattering solution to the exact (not linearized) inhomogeneous Helmholtz wave equation. This solution provides separate and independent images of density RHO, compressibility KAPPA, and absorption alpha. The spatial resolution of each of these three images is extremely high, near 250 microns or 1/2 wavelength at 3 MHz. Samples of breast cancer, benign tumors and other tissue will be scanned. This proof of concept will lead to construction of a full-scale scanner for SBIR Phase II clinical trails.